Experimental Study And Optimization Design Of Negative Tpressure Drying Machine For Agricultural Products

At present,there are many problems such as high energy consumption,heavy pollution,low efficiency,high equipment cost,difficult installation and transportation in domestic agricultural products drier,In recent years,most of the new drying equipment is designed for large quantities of grain drying,there is a lack of fine drying equipment for small batch of agricultural and sideline products drying,especially for chrysanthemum,lentinula edodes,fungus,Chinese herbal medicine and other economic crops.In order to solve the above problems,a kind of negative pressure electric heating agricultural product drying machine was designed in this paper..Negative pressure air inlet and exhaust technologies were used by the drying chamber to make full use of the pressure difference between the drying chamber and the outside world and the preheating of the exhaust pipe to the cold air,this method effectively improved the drying efficiency of dryer,meanwhile,the drying chamber was used to make the material dry even more.To verify the drying performance of the dryer,drying experiment of chrysanthemum were made.A mathematical regression model of the chrysanthemum dryer had been established according to the objective function,The objective function of the model were the color difference of chrysanthemum and the power consumption.According to the model,the influence for objective function was made by the interaction effect between the various factors.)Experimental results show that there were some problems such as the drying efficiency was low,Slow exhaust wet air,uneven air volume in drying room.Numerical simulation analysis of dryer were made by Fluent software,the numerical simulations showed that the flow field distribution in drying chamber had small airflow intensity,the distribution was not uniform and the air gap existed between the material layer and the wall of the drying room.Three optimization schemes(adjust the inlet size,change the wind pressure of the fan and add the wind deflector)were proposed basing on the drying experiments and mathematical regression model.The simulation results showed that the scheme of adding guide plate and adjusting the inlet size had obviously improved the three indexes of strength,uniformity and economy.